/*
 * Created on Jul 12, 2008
 * Created by Paul Gardner
 * 
 * Copyright (C) Azureus Software, Inc, All Rights Reserved.
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License only.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
 */

package com.aelitis.azureus.core.security;

import java.math.BigInteger;
import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.spec.KeySpec;

import org.bouncycastle.jce.ECNamedCurveTable;
import org.bouncycastle.jce.interfaces.ECPrivateKey;
import org.bouncycastle.jce.interfaces.ECPublicKey;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.jce.spec.ECNamedCurveParameterSpec;
import org.bouncycastle.jce.spec.ECParameterSpec;
import org.bouncycastle.jce.spec.ECPrivateKeySpec;
import org.bouncycastle.jce.spec.ECPublicKeySpec;
import org.bouncycastle.math.ec.ECPoint;

public class CryptoECCUtils {
    private static final ECNamedCurveParameterSpec ECCparam = ECNamedCurveTable.getParameterSpec("prime192v2");

    public static KeyPair createKeys()

    throws CryptoManagerException {
        try {
            KeyPairGenerator keyGen = KeyPairGenerator.getInstance("ECDSA", BouncyCastleProvider.PROVIDER_NAME);

            keyGen.initialize(ECCparam);

            return keyGen.genKeyPair();

        } catch (Throwable e) {

            throw (new CryptoManagerException("Failed to create keys", e));
        }
    }

    public static Signature getSignature(Key key)

    throws CryptoManagerException {
        try {
            Signature ECCsig = Signature.getInstance("SHA1withECDSA", BouncyCastleProvider.PROVIDER_NAME);

            if (key instanceof ECPrivateKey) {

                ECCsig.initSign((ECPrivateKey) key);

            } else if (key instanceof ECPublicKey) {

                ECCsig.initVerify((ECPublicKey) key);

            } else {

                throw new CryptoManagerException("Invalid Key Type, ECC keys required");
            }

            return ECCsig;

        } catch (CryptoManagerException e) {

            throw (e);

        } catch (Throwable e) {

            throw (new CryptoManagerException("Failed to create Signature", e));
        }
    }

    public static byte[] keyToRawdata(PrivateKey privkey)

    throws CryptoManagerException {
        if (!(privkey instanceof ECPrivateKey)) {

            throw (new CryptoManagerException("Invalid private key"));
        }

        return ((ECPrivateKey) privkey).getD().toByteArray();
    }

    public static PrivateKey rawdataToPrivkey(byte[] input)

    throws CryptoManagerException {
        BigInteger D = new BigInteger(input);

        KeySpec keyspec = new ECPrivateKeySpec(D, (ECParameterSpec) ECCparam);

        PrivateKey privkey = null;

        try {
            privkey = KeyFactory.getInstance("ECDSA", BouncyCastleProvider.PROVIDER_NAME).generatePrivate(keyspec);

            return privkey;

        } catch (Throwable e) {

            throw (new CryptoManagerException("Failed to decode private key"));
        }
    }

    public static byte[] keyToRawdata(PublicKey pubkey)

    throws CryptoManagerException {
        if (!(pubkey instanceof ECPublicKey)) {

            throw (new CryptoManagerException("Invalid public key"));
        }

        return ((ECPublicKey) pubkey).getQ().getEncoded();
    }

    public static PublicKey rawdataToPubkey(byte[] input)

    throws CryptoManagerException {
        ECPoint W = ECCparam.getCurve().decodePoint(input);

        KeySpec keyspec = new ECPublicKeySpec(W, (ECParameterSpec) ECCparam);

        try {

            return KeyFactory.getInstance("ECDSA", BouncyCastleProvider.PROVIDER_NAME).generatePublic(keyspec);

        } catch (Throwable e) {

            throw (new CryptoManagerException("Failed to decode public key", e));
        }
    }
}
